The skilled artisan is familiar with a variety of coloring systems, depending on the requirement for the coloring, to provide color-changing cosmetic agents, particularly for keratinic fibers, such as, for example, hair. So-called oxidation coloring agents are used for permanent, intensive colors with suitable fastness properties. Such coloring agents typically include oxidation dye precursors, so-called developer components and coupler components, which together form the actual dyes under the influence of oxidizing agents, such as, for example, hydrogen peroxide. Oxidation coloring agents are characterized by excellent, long-lasting color results. The oxidizing agent (i.e., hydrogen peroxide), present in the oxidation coloring agent, in this case initiates not only the formation of the dyes, but it also breaks down oxidatively the hair's own color pigments (melanins), so that in the case of oxidative coloring, a lightening coloring is also possible simultaneously. In order to produce satisfactory coloring and lightening, oxidative coloring agents usually require an alkaline pH during use; optimal results are achieved in particular at pH values between 8.5 and 10.5.
Ammonia is the alkalizing agent of choice today for adjusting these pH values. Not only can the pH range necessary for dye formation be adjusted with ammonia, but ammonia also causes the swelling of hair to a greater degree than all other known alkalizing agents. At the same time, ammonia acts as a penetration agent or penetration aid, also to a greater extent than all other commercial alkalizing agents.
For these reasons, more intensive colors and significantly better gray coverage are obtained during use of ammonia in oxidative coloring agents in comparison with other alkalizing agents (such as, for example, potassium or sodium hydroxide, alkanolamines, or carbonates such as sodium carbonate or potassium carbonate).
Due to the greater color intensities from the outset, the fastness properties of the hair colors obtained with the aid of ammonia are also better. In particular, colored hair has the best washing fastness if ammonia was selected as the alkalizing agent.
The performance advantages associated with the use of ammonia are so diverse that ammonia is used in a great number of commercial oxidative coloring agents despite its unpleasant, pungent odor.
Extensive efforts to reduce the ammonia odor are already known from the literature. In this regard, there are three basic options for minimizing the odor: The literature gives as the first option the variation of the alkalizing agent and thereby the partial or total replacement of ammonia by odorless alternatives.
Thus, for example, there are a great number of formulations in which a mixture of ammonia and monoethanolamine or monoethanolamine alone is used as the alkalizing agent. A reduction in the ammonia content, however, generally results in a poorer penetration of the dyes into the hair, which as previously described is reflected particularly in poorer gray coverage and a poorer washing fastness. If the focus is on the development of especially lasting nuances, the use of monoethanolamine is not an option for this reason.
WO 2006060570 and WO 2006060565 propose the use of carbonates or carbonate sources as alkalizing agents for providing oxidative coloring agents with less of a pungent odor. It is also known from the literature, however, that carbonates in combination with oxidizing agents can damage hair to a greater extent. The additional hair damage caused by carbonates may be less problematic during use of the coloring agent on untreated or undamaged hair, but can add up to serious cumulative damage in persons who dye or bleach their hair regularly. If greater lightening and/or regular coloring are desired, the use of carbonates therefore is also not a feasible alternative.
A second basic option for reducing the ammonia odor is the addition of special perfume substances, which are intended to cover the ammonia odor. This approach is used, for example, in WO 2005/110499. Perfume substances can be unstable under alkaline storage conditions, however, so that there is the risk that the aromatic substances are broken down or changed structurally during storage, which is also reflected in an unpredictable change in the odor. Because corresponding changes are often perceptible only after several months or even years, the use of new or unknown perfumes is regarded as problematic.
A third basic option for reducing the ammonia odor is an optimization of the formulation. In this case, the carrier ingredients of the formulation are to be selected so that they assure optimal retention of the ammonia in the formulation and minimize its odor in this way. It is also known, however, that the formulation, the fatty substances it includes, its emulsifiers, surfactants, and the viscosity as well have a major effect on the coloring performance. When the formulation is modified, deterioration of the coloring performance must therefore be prevented in every case.
For example, JP 2007191459 proposes using cationic surfactants, phosphate esters, and aliphatic alcohols to reduce the ammonia odor in hair coloring agents.
JP 2003040750 discloses that the ammonia odor in bleaching agents is especially low if at least 5% of a crystalline component is added to the agents.
In particular, the lasting odor minimization over the entire application period is only very difficult to achieve. The time period within which the user of hair dyes is in contact with the coloring agent extends from the preparation of the application mixture, its application to hair and the treatment time, up to the washing out of the formulation. At typical treatment times of 30 to 45 minutes, the entire process can take up to 90 minutes, at most up to 2 hours. Covering the ammonia odor, which is effective for this entire time period, poses the ultimate challenge. There is a still greater need for optimization in this field specifically, and an optimal approach for a lasting reduction of the ammonia odor is not known in the state of the art so far.
It is therefore desirable to provide agents for the oxidative coloring and/or lightening of hair with a reduced ammonia odor. In this regard, the agents should not exhibit any decreases in their dyeing performance, particularly in their gray coverage and their washing fastness. Moreover, the use of the agents should not be associated with greater hair damage, and they should be easy to use and storage-stable.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.